public void calculateNops(NopProject project){
	UserSession nextSession = 
		repository.getUserSessionAfter(project.getLastUpdate());
	if(nextSession == null) return;
		...
	while(nextSession != null){
		...
		project.update(nextSession.getEndTime());
		nextSession = 
	      repository.getUserSessionAfter(project.getLastUpdate());
		...
	}
	...
}